1. Field of the Invention
The techniques disclosed in the specification of the present application relate to method, apparatus, system, and program for storing data generated by a client.
2. Description of the Related Art
Among a number of different known methods for archiving data, each method has certain disadvantages. Until recently, archiving with tape has been the most commonly used method for archiving data. However, tape archives are often difficult to access (including read, write, acquire states thereof, and the like) and do not allow quick and easy retrieval of archived data. Because of this, disk arrays have become more common as the archival medium of choice, since they allow archived data to be more quickly and easily accessed. Although the archive usually means long-term preservation, the archive as used in the present specification needs not be interpreted as limiting to the one purposing the long-term preservation but means preservation.
Fixed Content Aware Storage (FCAS) is generally defined by SNIA (Storage Networking Industry Association) as storage of unchanging data (fixed content) and associated metadata based on a variety of naming schemas including Content Addressable Storage (CAS) and global content-independent identifiers. An example thereof includes an eXtensible Access Method (XAM) adopted by the SNIA. In the storage industry, CAS is also sometimes referred to as Content Addressed Storage, Content Aware Storage or Content Archive Storage.
In CAS, the content data to be generated and updated in a client coupled to the CAS is not processed as a standard file but is handled as an object which is composed of content data and metadata (which represents more than one attributes related to the content data). In this specification, when an object clearly shows that it contains the content data, the object is sometimes referred to as an content object. The content data is appended with metadata and is assigned a unique content object identifier known as “object ID.” For archiving, the content object is stored to several locations on a hard disk. Then, the client refers to or edits the content data or the metadata of the object archived in the CAS by designating the object ID.
There is known a method in which a so-called NAS (Network Attached Storage) is used in archiving.
In NAS, the client identifies files by the use of a path name composed of a directory name and a file name, management of files, typified by generate, update or delete, is carried out. Moreover, in the NAS, by designating a directory name of a directory in which more than one files are included, it is possible to collectively perform operations to the more than one files included in the designated directory. For this reason, the NAS is sometimes referred to as file storage.
As an example implementation of the file storage used in archiving, U.S. Pat. No. 7,155,466 discloses a storage system and data management method.